Is it a boycott if a person already knows that will never use their products and services ever again?
You ask the right question ... yes it is a boycott if you cease to use a normally used produce or service, not a boycott if you don’t. However in many cases the company marketing types may already have you profiled as a user or non-user. If they recognize you as a non-user, your continued non-use is of no concern to them. It is a bit like writing to your democrat congressman and starting your letter with ‘I am a Republican ...’ or ‘I didn’t vote for you ...’. The cipher reading your letter stops right there and drops your letter into the shredder. They - don’t - care ... although you may get a boilerplate response that says “Thank you for contacting this office. We will give your opinions the consideration that WE feel they deserve.”
IOW, F.O.A.D.